The present invention relates to railway track bonding wires and, more particularly, to the fastening devices for maintaining the wires in place adjacent the rail.
Generally in order to provide good electrical conductivity across joints in a track circuit it is necessary to bond the rail joint. This has been accomplished in the past by drilling a hole in each end of the rail and bridging the joint by one or more conductors known as bond wires. Usually the bond wires have sufficient slack that the wires are susceptible of being bent over onto the ball of the rail where they can be cut by the wheels of passing trains. Alternatively, they can be displaced down onto the ballast in which position they are likely to be damaged through the ignorance of the track men or torn from the rails by dragging rigging on the trains. Thus, for various reasons there has been a continuous need for clamps or the like to hold the wires in fixed safe position alongside the rail.
For this purpose, one railroad system employs a pair of fasteners, one a wire retaining clip and the other a wire keeper, for holding the bond wires in place. The devices consist of straps or strips fabricated from mild steel that has been zinc coated by dipping in molten zinc. The known retaining clip has one end consisting of a rectangular section of sheet metal, a rectangular aperture centered in the rectangular section, the rectangular section being bent U-shape with the bend or bight of the "U" bisecting the aperture running in the short direction across the section. Two parallel elongated spaced apart rectangular legs of sheet metal extend from one short side of the rectangular section. Down the longitudinal centerline of the rectangular section, between the border of the aperture and the adjacent side of the rectangular section, the metal is formed semi-cylindrical so as to provide confronting channels for securing a bond wire in a bight configuration wrapped over the lateral edge of a rail flange.
In use, the known retainer is placed with its legs slipped under a rail base from one side so that the rail flange slips into the U-shape section, whereupon the free end of each leg is manually formed around the opposite side of the rail base and tapped down with a hammer. However, bending of the legs of the retainer around the rail base tends to crack the zinc coating exposing the base metal to the elements, and corrosion sets in prematurely. Also, the known retainers, being constructed of mild steel, are easily unbent from the rail base without the aid of tools and have been subject to vandalism. Vibration from passing rail cars and brush contact from track sweeping operations tend to cause the retainers to creep. Also, the bond wire keeper, a retainer with a single semi-cylindrical portion at its end intended to clamp the wire against the flange where it meets the web of the rail lacks sufficient tension to maintain adequate pressure on the bond wire to resist relative movement of the bond wire. Consequently, the wire is susceptible of "gapping" or otherwise becoming loose thereby subjecting the wire to potential damage from track and ballast maintenance operations.
It is, therefore, an object of the present invention to provide a bond wire retainer system that is vandal resistant.
Another object is to provide a retainer system that resists creep and displacement so as to retain its as-installed retention capacity.
Yet another object is to provide retaining clips and keepers that are more corrosion resistant than those heretofore available.